Using science for more animal welfare

Foie gras, translated from French as “fatty liver”, is known in Germany as “Gänsestopfleber” (goose liver). For animal welfare reasons, the so-called “force-feeding” has been criticized for a long time, and in many countries its production or even sale is prohibited. Substitute products have so far been unable to imitate the unique taste and texture of foie gras.

Researchers led by Thomas Vilgis from the Max Planck Institute for Polymer Research (MPI-P) in Mainz, together with colleagues from the University of Southern Denmark, have now used various scientific methods to examine the structure of real foie gras and developed an alternative based on these findings.

“It has always been a goal to reproduce the taste and texture of real foie gras while not losing sight of animal welfare,” says Thomas Vilgis, himself a passionate amateur chef and scientist at the MPI-P.

For their investigations, the researchers used both microscopic methods to determine the fat content or the proportion of collagen fibers, which account for a large part of the mouthfeel, and so-called rheological investigations. In the latter, the “processing” of the foie gras in the mouth is simulated by means of appropriate mechanical setups and expressed in figures.

In order to produce a new, animal-friendly foie gras, the researchers cooked collagen-rich tissue such as skin and used it to make a gel. This gel is then mixed with liver and fat in the correct proportions to form a pâté. However, despite similar ingredients, this mixture could not adequately imitate the “real” product, and even the systematic addition of collagen did not produce a better result. The scientists then had the idea of treating the fat with the goose's own lipases. Lipases are enzymes that help to digest fat in the body and mimic the natural processes in the duck's body.

The pâté produced in this way closely mimics the properties of real foie gras. This is mainly due to the restructured fat, because it is only the lipase treatment that allows the formation of large (irregular) fat aggregates, as they also occur in foie gras. This is the best way to imitate the mouthfeel and, above all, the melt. Collagen-enriched pâtés do not allow for this.

For Vilgis and his team, it was important not to add any external ingredients or additives to the foie gras. Vilgis has already applied for a patent for the recipe and hopes to work with companies that can help in the production of the alternative product. He would also like to work with sensory experts who can help him refine the taste and smell of foie gras.

The research results have now been published in the journal Physics of Fluids.